Need help designing online psychotherapy site

Hi, 

I have built a Squarespace site successfully and now want to build a new business. But need help (unpaid or paid can be considered as well) and advice for the ambition. 
 

essentially, I want a global site which has therapists worldwide. People book through each therapists location and time availability on calendar. After that the booking is confirmed via email if they pay successfully through stripe. We then need a record of who has paid or booked for admin reasons but stored in a secure way for data privacy reasons. How do I go about building this on Squarespace ? Thanks